The present invention relates to an open-end spinning device having a spinning rotor rotating in a rotor housing with a spinning insert arranged rotatably supported within the spinning rotor coaxially to the rotor axis.
German Patent Publication DE-OS 25 52 955 teaches rotatably supporting a spinning insert inside the spinning rotor of an open-end spinning device. The rotor shaft of the spinning rotor is designed as a hollow shaft and rotates on a support disk mounting. The drive and bearing shaft of the spinning insert is supported in the hollow shaft by roller bearings. The spinning rotor and the spinning insert are driven by a common tangential belt. In order to achieve a necessary speed difference between the spinning rotor and the spinning insert in such rotor spinning devices, the drive whorls of the two shafts have different dimensions. This open-end spinning device is intended to be able to eliminate disadvantages in the nature of the rotor spun yarn such as, e.g., reduced yarn strength, that are inherent in a yarn produced with this spinning method in contrast to the ring spinning method. However, open-end rotor spinning devices of this type have not proven themselves in practice.
German Patent Publication DE 44 11 342 A1 also describes an open-end spinning device with a spinning insert rotatably supported in the spinning rotor. The spinning insert can be intermittently fixed on the spinning rotor via a coupling device. In normal spinning operation the spinning insert is driven by the rotating shank of the yarn being spun. It is possible by means of the coupling device to accelerate the spinning insert to the rotor speed in the acceleration phase of the spinning device in that the spinning insert is entrained by the spinning rotor. This avoids an overloading of the yarn during a piecing operation that could result in a yarn break or in a failure of the piecing operation. The coupling is designed as a centrifugal coupling or, alternatively, as an electromagnetic coupling with a frictional contact between the spinning rotor and the spinning insert via spring elements. The time of the entrainment of the spinning insert by the spinning rotor must be adjusted in a defined manner and subsequently corrected if necessary. A disadvantageous roughening of the surface and wearing over a long period of operation can occur on the spring elements and the spinning rotor. A release of the coupling and thereby the cancellation of frictional contact connecting the spinning rotor and the spinning insert can not be coordinated to the extent desired exactly with the time of the piecing-up of the yarn during the piecing process. After the piecing of the yarn, the coupling must be released in order that different rotational speeds of the spinning rotor and of the spinning insert are possible. If the coupling is released too late, this can result in a defective yarn piecing.